The present invention is an improvement on the apparatus used to mount discs on the spindle hub of a disc drive motor. Conventionally, the motor is located within the spindle hub of the disc drive and one or more discs coated with magnetic material are attached to the spindle hub.
To facilitate mounting the discs, a flange protrudes from the cylindrical hub and the first disc rests upon that flange. Alternating spacer rings and discs are stacked upon the first disc. A clamp ring is attached to the opposite end of the cylindrical hub to apply pressure to the disc and spacer ring stack, thereby firmly holding the discs in a fixed position against the cylindrical hub.
The motor rotatably drives the hub and discs, allowing the information stored thereupon to be accessed by a multitude of read/write heads. These heads "float" a small distance above the disc surface to sense the small magnetic signals stored upon the discs. The firm positioning of the discs is critical to accurate disc drive operation. The magnitude and location of the force imparted by the clamping ring is of critical importance to maintaining the position of the discs. Without proper clamping force, the discs, especially the first disc abutting the flange, will move perpendicular to the direction of rotational motion causing off-track error or the disc may impact the heads causing permanent disc drive damage.
Previously, the disc mounting flanges have been machined to have a flat mounting surface. This provided maximum surface area for the disc to rest upon, but did not position the clamping force in an optimal location. In this situation, the clamping force is maximized near the cylindrical hub. This force distribution will tend to bow the disc and spacer stack causing the discs to no longer be parallel to each other. In other words, the first disc, as well as others, would tend to move perpendicular to the direction of motion due to the clamping force distribution not having a maximum at a location away from the cylindrical hub. As the flange is bent downward forming an arc, a gap will form between the flange and the disc. The foregoing description of the prior art having a flat mounting surface is depicted in FIGS. 2A and 2B. Other prior art use a flat, but raised mounting area as shown in FIGS. 3A and 3B. This arrangement results in the same problems, i.e., unaligned clamping forces, as was discussed in connection with FIGS. 2A and 2B.
An objective of the current invention is to provide a specially designed disc mounting flange that imparts a clamping force that securely mounts the discs to the hub.
Another object of the present invention is to provide a disc mounting flange which has a raised disc resting surface which is in line with the clamping force applied by the clamping ring. The maximum force now occurs at a point away from the hub surface, and remains on that point while the flange bends under the clamping force.